The Occupational Health Branch (OHB) of the California Department of Health Services (CDHS) proposes to develop a method for direct laboratory reporting of blood cholinesterase test results and to assess the efficacy of this system as a method for surveillance of illness due to cholinesterase-inhibiting pesticides. OHB currently conducts surveillance of work-related diseases, including pesticide illness, primarily through mandatory physician reporting. The use of laboratories as a source of information to supplement current pesticide illness surveillance activities will be explored. Impending regulations to standardize cholinesterase test reporting in California present a unique opportunity to study the utility of direct laboratory reporting as a surveillance method. This project proposes a prospective passive surveillance system for the detection of pesticide illness through direct laboratory-based reporting. Three laboratories will be initially requested to voluntarily report to OHB the results of all cholinesterase tests performed on California patients. Occupational pesticide illness cases will initially be identified through telephone follow-up of health care providers. Laboratory requisition forms will be modified or new forms developed to facilitate the identification of occupational pesticide-related cholinesterase tests and the forms will be tested for physician acceptance and compliance. If compliance is demonstrated, suspected occupational pesticide-related cases will be identified through laboratory reports, not solely through physician follow-up. All suspected cases will be contacted by bilingual interviewers for completion of an interview to assess issues related to pesticide illness and exposure at work. The NIOSH case classification system for pesticide illness will be used. Data abstraction, entry, and analysis will be conducted using strict quality control. Various information technologies will be explored for routine reporting of blood cholinesterase test results: hard copies will initially be requested; if acceptable, electronic reporting will be established by the end of the project. Surveillance data gathered by the research project will be evaluated for its ability to detect additional occupational pesticide illness cases. Under-reporting of illness due to cholinesterase inhibiting pesticides will be assessed by comparison of data obtained by this research project with physician reported cases in the current surveillance system. The data will also be used to identify populations at risk for illness due to cholinesterase inhibiting pesticides and the work tasks associated with illness. If the proposed research shows that reports of cholinesterase test results contribute significantly to occupational pesticide illness surveillance, OHB will consider introducing laboratory-based reporting as a requirement in legislation